rem sendero please help

my buddy just bought a rem sendero in 300 rem ultra mag having weird problems gun shoots same hole for a few then 3 to 9 inches right then will come back after a few then back to the right again this gun is brand new with muzzle brake but doesnt matter brake or no brake tried two diffrnt scopes samething we have 4 of the identical guns with having no problems except for this one shooting 208gr A-maxes but how can a gun shoot same hole then go way out then come back checked all obvious things any ideas would help thanxs